• Journal of the Korean Society for Nondestructive Testing
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• 제28권1호
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• pp.59-63
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• 2008

Time reversal (TR) of nondispersive body waves has been used in many applications including ultrasonic NDE. However, the study of the TR method for Lamb waves on thin structures is not well established. In this paper, the full reconstruction of the input signal is investigated for dispersive Lamb waves by introducing a time reversal operator based on the Mindlin plate theory. A broadband and a narrowband input waveform are employed to reconstruct the $A_0$ mode of Lamb wave propagations. Due to the frequency dependence of the TR process of Lamb waves, different frequency components of the broadband excitation are scaled differently during the time reversal process and the original input signal cannot be fully restored. This is the primary reason for using a narrowband excitation to enhance the flaw detectability.

• Preventive Nutrition and Food Science
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• 제13권4호
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• pp.281-285
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• 2008

Cherry tomatoes are rich in antioxidants, which may protect against neurodegeneration and consequent memory loss. This study was conducted to investigate the effect of cherry tomatoes on scopolamine-induced amnesia in mice. Male ICR mice (4 weeks old) were maintained for 4 weeks on a diet containing 10 or 20% tomato powder (TP), and then administered scopolamine (1 mg/kg body weight, i.p.) 45 min before memory testing. Passive avoidance and Morris water maze testing revealed that scopolamine-induced amnesia was significantly reduced in the TP groups compared to the non TP-received (control) group. Accordingly, acetylcholinesterase activities in the serum and brain of TP groups were lower than those in the control group. These findings suggest that cherry tomatoes may be useful for the prevention of neurodegenerative diseases such as amnesia and Alzheimer's disease.

• KSBB Journal
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• 제31권1호
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• pp.46-51
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• 2016

Recently paper based diagnostic kits have drawn great interest in the point-of-care testing market (POCT). The paper based detection systems provide inexpensive, rapid and safe analyses for disease markers and/or pathogens. Vitamin C (i.e., ascorbic acid) regulates body's immune system as an antioxidant agent. Humans, however, do not have enough amounts of enzymes involved in the synthesis of vitamin C that it is required to be obtained from their diets (e.g., beverages and/or supplements). Here, we have prepared a paper based kit to detect the concentration of Vitamin C presented in commercially available beverages. The evaluation provides the fast, simple and accurate results for detecting Vitamin C in the prepared paper based kit.

• Journal of the Korean Society for Aviation and Aeronautics
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• 제17권4호
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• pp.42-47
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• 2009

Recently, the wide range of the composite materials is used for the making airplanes, trains and automobiles body for the lightweight. Despite having complex structures, composite materials usually have well defined mechanical characteristics. However, composite materials are difficult to understand the fracture mechanism clearly by simple mechanical test. Nondestructive evaluation (NDE) combined with mechanical testing can play a more important role and especially Acoustic Emission Testing (AET) would become known to be a useful tool to assess damage and fracture behavior of composites. In this study The experiment was performed to acquire the acoustic emission signal during tensile test using unidirectional CFRP specimen and the data was analyzed the acoustic emission parameters with the waveform.

• Journal of the Korean Society for Railway
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• 제7권1호
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• pp.32-36
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• 2004

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody. The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

• Journal of Korea Multimedia Society
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• 제16권12호
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• pp.1376-1384
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• 2013

In this paper, we propose an automaticdetection method of foreign bodies through template matching in industrial CT volume data. Our method is composed of three main steps. First,Indown-sampling data, the product region is separated from background after noise reduction and initial foreign-body candidates are extracted using mean and standard deviation of the product region. Then foreign-body candidates are extracted using K-means clustering. Second, the foreign body with different intensity of product region is detected using template matching. At this time, the template matching is performed by evaluating SSD orjoint entropy according to the size of detected foreign-body candidates. Third, to improve thedetection rate of foreign body in original volume data, final foreign bodiesare detected using percolation method. For the performance evaluation of our method, industrial CT volume data and simulation data are used. Then visual inspection and accuracy assessment are performed and processing time is measured. For accuracy assessment, density-based detection method is used as comparative method and Dice's coefficient is measured.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제19권2호
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• pp.110-115
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• 2016

Purpose: We performed to reveal the association between the Helicobacter pylori infection and body weight among children. Methods: Out retrospective study included patients who underwent the H. pylori immunoglobulin G testing at Konyang University Hospital between March 2011 and June 2014. These patients were classified as seropositive (28 boys, 27 girls; mean age: $9.89{\pm}3.28years$) or seronegative (55 boys, 54 girls; mean age: $9.84{\pm}3.02years$). Next, we compared various characteristics between the seropositive and negative groups, as well as between obese children (body weight ${\geq}90th$ percentile) and non-obese children (body weight <90th percentile). Furthermore, we compared the change in body weight after 2 months of treatment with amoxicillin, clarithromycin and omeprazole among the 55 seropositive children (14 treated children and 41 non-treated children). Results: There were no differences in the weights and laboratory data for the 55 seropositive children and 109 seronegative children (weight; $40.96{\pm}18.11kg$ vs. $36.85{\pm}13.72kg$, respectively; p=0.14). And, there was no difference in the prevalence of H. pylori infection among the 29 obese and 135 non-obese children (p=0.581). However, after 2 months of eradication, the 14 treated patients exhibited a significant weight gain ($+0.91{\pm}0.52kg$), compared to the 41 non-treated patients ($-0.29{\pm}1.16kg$, p=0.025). Conclusion: Our findings present that obesity was not associated with the H. pylori infection, although H. pylori eradication led to significant increase in body weight.

• Journal of the Korean Geotechnical Society
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• 제23권4호
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• pp.33-46
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• 2007

HWAW (Harmonic Wavelet Analysis of Wave) method, which is non-destructive method using body and surface waves, has the advantages of obtaining 2D subsurface imaging because it uses a short receiver spacing to obtain the $V_s$ profile of whole depth. Even though the reliability of HWAW method has already been verified by using the numerical simulation in the various layered models, it is very difficult to evaluate the reliability of HWAW in the field because the exact $V_s$ values of the experimental site are unknown. In this study, a model testing site where the material properties and layer information could be controlled was constructed to verify the reliability of HWAW method. The detailed geometry of the testing site was strictly measured by surveying, and 140 vertical and horizontal geophones were established at the boundary of each layer to evaluate the dynamic material properties. Using the interval travel times between the upper and lower geophones, the body wave velocities of each layer were 2 dimensionally obtained as reference data, and comparative study using HWAW method was performed. By comparing 2D Vs profile obtained by HWAW method to the reference data, the reliability of HWAW method was verified.

• The Journal of the Convergence on Culture Technology
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• 제10권3호
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• pp.7-11
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• 2024

The bedsore prevention cushion serves to prevent the skin on the buttocks of a wheelchair user from being damaged through friction with the wheelchair seat. This is because it absorbs some of the weight applied to the wheelchair seat and allows the weight to be applied evenly to the entire contact surface. For the impact test, which is part of the performance testing of bedsore prevention cushions, a hip model that represents the sitting posture of a wheelchair user is required. In this study, a hip model was manufactured for impact testing of bedsore prevention cushions for wheelchairs. Performance tests for pressure bedsore prevention cushions for wheelchairs include KSP 0236, a Korean standard, and KS P ISO 16840-2, an ISO international standard. The hip model proposed in KS P ISO 16840-2 was more suitable for impact testing of bedsore prevention cushions for wheelchairs. However, the guidelines for making hip models proposed by international standards need to be modified to reflect the advancement of model making technology and use easier methods. We propose a new hip model production method that produces a hip model out of plastic all at once and additionally attaches SS-41 steel plates processed into the shape of the hip to make the mass of the model similar to the human body.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2004년도 추계학술발표대회 개요집
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• pp.165-167
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• 2004

The failure pressure for corroded pipeline was measured by burst testing and classified with respect to corrosion sizes and corroded regions - the body, the girth weld and the seam weld of pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.